a. The Field of the Invention
This invention relates to road surface marking tape materials for use on a roadway pavement so as to provide a traffic regulating indicium thereon, and more particularly this invention relates to a new and improved tape material of the general character described in my prior U.S. Pat. No. 3,782,843 (U.S. patent application Ser. No. 153,218 filed June 15, 1971), corresponding to my French Patent No. 2,097,941, Swedish Patent No. 361,694, and German Patent Application No. P 2130529, open to public inspection.
B. The prior Art
According to the above prior art, upon which the present invention provides a sharp improvement, there has been suggested and made known a marker for use on a roadway pavement, comprising a base compound including a binder and having a smooth, substantially planar and highly light-reflective surface adapted to face away from said pavement, and a plurality of hard crystalline particles, each having a largest dimension between substantially 0.1 and 1 millimeters, and at least some of which include an upper portion extending outwardly from said surface to impart good anti-skid properties to the same surface, while the light reflectivity of the marker in use on the road pavement is high due to the small fraction of the total area of said surface constituted by said upwardly extending upper portions of the hard crystalline particles.
Further according to said prior art, the said hard particles are firmly bound and secured to the marker material base compound, including the said binder, by a second binder intimately contacting each individual particle, said second binder wetting said particles when contacted therewith and being compatible with said first binder.
Still further according to said prior art, the said very hard particles comprise crystals having a hardness substantially higher than 7 on the Mohs' Hardness Scale and more particularly corundum crystals, coated with epoxy resin before being added to and mixed with the base compound. This latter compound preferably consists of a mixture of binder agents, such as butadiene-acrylonitrile copolymeric rubber and polyvinyl chloro-acetate copolymer, and fillers, such as titanium dioxide, kaolin, calcium carbonate and so on, adapted for imparting the desired color to the tape material.
The object of this invention is to provide a new and improved road surface marking tape material, generally of the kind and for the use set forth above, sharply improved in comparison to the above indicated prior art so that the combination of the following principal advantages is attained:
the new material provides a highly light reflective and anti-skid upper surface having an improved wear resistance against traffic, and the anti-skid properties of which are substantially maintained even after substantial wearing-off of the tape upper layer upon extensive service and traffic abuse;
the new material provides an improved and uniform bond with the generally bitumen based underlayer or receiving layer (generally termed "primer" layer in the specific art to which this invention appertains) preliminarily and commonly freshly formed on the roadway pavement to provide an impervious, uniform and smooth surface area on which the marking tape material can be laid and adhesively secured;
the new material is particularly adapted for ready and economical manufacture on a mass production basis and does not require the step of individually coating the particles which impart the anti-skid properties, while the firm bond of even partially embedded particles with the material is ensured and even improved;
the new material may be and preferably is also provided with light retro-collimating units or aggregates for improving the nighttime visibility of the traffic regulating signs or indicia, the features of the new material being such as to ensure the firm bond and the most efficient service of said units or aggregates.